1. Field of the Invention
The present invention relates to a process for producing an aminophenol ether in high selectivity and high yield.
2. Description of the Prior Arts
Aminophenol ethers are useful as starting materials and intermediates for medicines, agricultural chemicals and perfumes. Various processes have been known. For example, it has been known to produce an aminophenyl alkyl ether by directly reacting an aminophenol with alkyl halide. However, in accordance with this process, it is difficult to selectively produce only aminophenyl alkyl ether in high yield since by-products of (b) N-alkylaminophenol and (c) N-alkylaminophenyl alkyl ether are producted together with the object compound of aminophenyl alkyl ether as shown in the following reaction formula ##STR3## wherein R.sub.1 represents an alkyl group; and X represents a halogen atom.
In order to dissolve these difficulties, the following processes have been proposed. (1) An aminophenyl alkyl ether is produced by protecting an amino group of aminophenol to convert it an acetamide group by an acetylation and then hydrolyzing the acetamido group. (See Nippon Yakugaku Zasshi 74 (1954) pages 872 to 875).
(2) An aminophenyl alkyl ether is produced by converting a hydroxyl group of aminophenol to sulfonic ester group (--SO.sub.3 Ar) by reacting sulfochloride and reacting a metal alcoholate as an alkylating agent. (See Nippon Yakugaku Zasshi 74 (1954) pages 872 to 875).
(3) An aminophenyl alkyl ether is produced by directly alkylating aminophenol by using a dialkyl sulfate as an alkylating agent. (See J. of Organic Chemistry Vol. 22 (1957) pages 333 to 334).
However, the process (1) has the disadvantage of requiring many steps so as to cause a high cost for producing the object compound of aminophenyl alkyl ether. Thus, the process is not satisfactory as an industrial process. The processes (2) and (3) have respectively the disadvantage that the production of the by-products of N-alkylaminophenol and N-alkylaminophenyl alkyl ether can not be satisfactorily prevented to be low selectivity and low yield of aminophenyl alkyl ether.